1. Field of the Invention
The present invention relates to a method for manufacturing an orifice plate for use of a liquid discharge that discharges a desired liquid by the creation of bubbles generated by the application of thermal energy or the like. It also relates to an orifice plate manufactured by such method of manufacture, a method for manufacturing a liquid discharge provided with such orifice plate, and a liquid discharge manufactured by such method of manufacture. The present invention is applicable to a printer, a copying machine, a facsimile equipment provided with communication system, a word processor provided with a printing unit, and some other apparatuses. It also applicable to an industrial recording system having various processing apparatuses combined comlexly therefor to make it possible to record on a recording medium, such as paper, thread, fiber, cloths, leather, metal, plastic, glass, wood, ceramic, or the like.
Here, for the present invention, the term "recording" referred to in the specification hereof means not only the provision of characters, graphics, or some other images that present some meaning when recorded on a recording medium, but also, means the provision of images that do not present any particular meaning, such as patterns recorded on the recording medium.
2. Related Background Art
There has been known conventionally a bubble jet recording method whereby to provide ink with heat or some other energy generated to cause its states to be changed with the abrupt voluminal changes in ink (the creation of bubbles) so that ink is discharged from a discharge port on the basis of acting force exerted by such change of states, thus forming images on a recording medium by the adhesion of ink to it. The recording apparatus that use this bubble jet recording method is generally provided with the ink discharge port for discharging ink; the ink flow path communicated with the discharge port, and heat generating devices (electrothermal converting devices) serving as energy generating means for discharging ink distributed in each of the ink flow paths as disclosed in the specifications of Japanese Patent Publication No. 61-59911 and Japanese Patent Publication No. 61-59914, among some others. In accordance with this recording method, it is possible to record high quality images at high speeds in a lesser amount of noises. At the same time, it is possible to arrange the ink discharge port in high density for the head that adopts this recording method. Therefore, images can be recorded in high resolution by use of a smaller apparatus, while making it easier to obtain color images, among many other advantages. As a result, the bubble jet recording method has been widely used for office equipment, such as a printer, a copying machine, or a facsimile equipment in recent years. This method has been utilized also for a textile printing apparatus, and other industrial recording systems as well.
Along with the utilization of bubble jet technologies and techniques in the various fields of application, there has been a strong demand on the provision of a recording apparatus which is capable of recording in higher resolution at lower costs.
Here, the ink discharge port are formed on an orifice plate. Usually, however, the orifice plate is adhesively bonded to the liquid discharge main body side by the application of adhesive or the like subsequent to the discharge port having been formed on it.
Now, hereunder, the detailed description will be made of the conventional method for manufacturing an orifice plate.
FIGS. 17A to 17C are views which illustrate the steps of manufacture in accordance with the conventional method for manufacturing an orifice plate.
At first, using the photolithographing method the resist 307 is formed in a specific position on the substrate 301 (FIG. 17A).
Then, on the substrate 301 having the resist 307 formed on it, nickel 308 is formed by use of electroforming (FIG. 17B).
After that, the resist 307 and the substrate 301 are peeled off from the nickel 308 one after another in that order in order to form the discharge port 302 (FIG. 17C).
Also, there is a method for manufacturing an orifice plate with resin instead of using the electroforming method described above.
Of the liquid discharges manufactured by use of these methods, there is the one whose printing reliability has been enhanced by trapping ink adhering to the face by a face pattern (the discharge opening surface having the water-repellent pattern on the circumference of the surface of the discharge port and the hydrophilic pattern on the portion away from the circumference thereof). Here, the face pattern of the kind is obtainable by the irradiation of excimer laser on the resin sheet.
However, in accordance with the conventional method, the resist is formed in advance on the portion where the discharge port is formed, and then, by use of the electroforming, nickel is formed in order to provide the orifice plate. After that, the discharge port are formed by peeling off the resist from the nickel. As a result, the step 310 is inevitably formed on the discharge port as shown in FIG. 17C. This formation of such step 310 is not desirable for the performance of effective ink discharges.
More specifically, if any ink which has increased viscosity should adhere due to the presence of this step, it is made difficult for the discharge energy to act upon the discharge of droplets effectively or if the configuration of each of such steps should vary, the discharge directivity is allowed to vary accordingly.
Here, the corner portion 311 formed by the step 310 makes it easier for discharging droplets to reside on that portion to cause the loss of discharge energy accordingly.
Also, when the hydrophilic pattern is formed by the application of laser, a problem is encountered that this formation makes it difficult to arrange the position of orifices in a sufficiently high precision.
Here, with a view to enhancing the abrasion resistance and durability of the orifice plate described above, it is desirable to use Ni or other metallic material for the orifice plate.
However, if the portion on the elemental substrate having the orifice plate, the ceiling plate, and the heaters arranged on it, which is in contact with ink, should be formed by metal or some other conductive material from the viewpoint of its manufacture, the liquid discharge and such portion become electrically conductive through ink (by the direct contact or through the adhesive) to present a cell structure which may in some cases satisfy the condition that allows electrolytic corrosion to occur.
If the orifice plate is left intact under such condition, the orifices on the orifice plate are dissolved to change the area of the orifice surface. Conceivably, therefore, the amount of discharges is made inconstant.
With a view to dealing with such condition as described above, the inventors hereof have taken up as one of the new subjects that the reliability of the orifice plate should be made invariable and more stabilized for a longer period.
Also, in consideration of each of the materials used for the inner structure of the liquid flow paths of a liquid discharge provided with the orifice plate, including, of course, its surface to be in contact with liquid as well as the external layer portions thereof, it is assumed that, in some cases, the inner structure may become electrically conductive, not necessarily directly as described above, but depending on the components contained in the liquid. In other words, the condition of electrolytic corrosion may be satisfied depending on some metallic ion or other ion contained in the liquid as the case may be. An ion of the kind may inevitably exist in the liquid flow paths due to the structure of liquid container serving as the supply-source of liquid or due to the unprepared supply of liquid other than the designated one. Therefore, it becomes a second subject to be taken up by the inventors hereof that even in such a case as described above, the reliability of the orifice plate should be made invariable and stabilized for a longer period.